AS & A Level Chemistry - 9701 Paper 1 2020 Summer Zone 1

Ethene can be oxidised to form epoxyethane, $C_2H_4O$.

$$C_2H_4(g) + \frac{1}{2}O_2(g) \rightleftharpoons C_2H_4O(g) \quad \Delta H^\circ = -107 \text{ kJ mol}^{-1}$$

Which set of conditions gives the greatest yield of epoxyethane at equilibrium?

[Table_1]

Cobalt can form the positive ion \(\text{Co(NH}_3\text{)}_4\text{Cl}_2^+\).
What is the oxidation number of cobalt in this ion?

When considering one molecule of ethene, which row describes both the hybridisation of the atomic orbitals in the carbon atoms and the overall bonding?
[Table_1]

10 cm$^3$ of ethane is burned in 45 cm$^3$ of oxygen at a pressure of 101 kPa and a temperature of 200 °C. Complete combustion takes place.
What is the total volume of gas present when the reaction is complete, measured under the same conditions?

Two reactions are shown.
$\text{H}_2(g) \rightarrow 2\text{H}(g)$
$\text{CO}(g) + \frac{1}{2}\text{O}_2(g) \rightarrow \text{CO}_2(g)$
If molar amounts are used, how can the two energy changes associated with these reactions be described?

The diagram shows the Boltzmann energy distribution curves for molecules of a sample of a gas at two different temperatures.
Which letter on the axes represents the most probable energy for molecules of the same sample of gas at the lower temperature?

What are the units of $K_p$ for the reaction shown?
$\text{H}_2\text{O(g)} + \text{C(s)} \rightleftharpoons \text{H}_2\text{(g)} + \text{CO(g)}$

In this question you should use changes in oxidation numbers to balance a chemical equation.
Acidified potassium dichromate(VI) solution can oxidise a solution of $\text{V}^{2+}$ ions. The equation for this reaction is shown.
$a\text{Cr}_2\text{O}_7^{2-} + b\text{V}^{2+} + c\text{H}^+ \rightarrow d\text{Cr}^{3+} + e\text{VO}_3^{-} + f\text{H}_2\text{O}$
What is the ratio $a : b$ in the correctly balanced equation?

A sample of argon gas has a mass of 0.20 g, at a pressure of 100000 Pa and a temperature of 12°C. Which volume does the gas occupy?

In which pair does each species have the same number of unpaired electrons?

A sample of solid ammonium chloride decomposes on heating.

solid ammonium chloride $\rightarrow$ ammonia gas + hydrogen chloride gas

A total of $2.4 \times 10^{21}$ molecules of gas is formed.

How many hydrogen atoms are present in the gaseous products?

A white powder is a mixture of sodium chloride and sodium iodide. It is dissolved in water in a test-tube. An excess of aqueous silver nitrate is added to the test-tube. A precipitate, X, is observed.
An excess of concentrated ammonia is then added to the test-tube containing X. After the test-tube has been shaken, a precipitate, Y, is observed.
Which statement about X or Y is correct?

6.90 g of an ammonium salt is heated with an excess of aqueous sodium hydroxide. The volume of ammonia produced, measured under room conditions, is 2.51 dm³. Which ammonium salt is used?

An excess of MgO is shaken with water. The resulting mixture is filtered into test-tube P.
An excess of BaO is shaken with water. The resulting mixture is filtered into test-tube Q.
Which oxide reacts more readily with water and which filtrate has the lower pH?

[Table_1]

Element Z has a giant structure.
The chloride of Z reacts with water to give a solution with a pH less than 5.
Which pair shows two elements which could be Z?

Sodium, aluminium and silicon are three elements in Period 3. Each element forms an oxide. Which row has three correct properties of these oxides?
[Table_1]

0.25 g of anhydrous magnesium nitrate is heated strongly until it completely decomposes.
What is the total volume of gas produced, measured under room conditions?

Astatine, At, is below iodine in Group 17 of the Periodic Table.
Which statement is most likely to be correct?

What is the order of increasing melting point of the three chlorides shown? $$ \text{CCl}_4 \quad \text{MgCl}_2 \quad \text{PCl}_5 $$ [Table_1]

The skeletal formula of compound X is shown.
Which row is correct?
[Table_1]

Which statement is correct?

But-1-ene and but-2-ene are treated separately with cold, dilute acidified manganate(VII) ions. Four students, W, X, Y and Z, make statements about these alkenes and the diols formed from them.
W One diol contains two primary alcohol groups.
X One diol contains a primary and a secondary alcohol group.
Y One diol contains two secondary alcohol groups.
Z Both alkenes exhibit cis-trans isomerism.
Which two students are correct?

2-bromo-2-methylpentane is a tertiary halogenoalkane.
Which organic products are formed when 2-bromo-2-methylpentane reacts with a hot concentrated ethanolic solution of sodium hydroxide?

Poly(propene) is an addition polymer. What are the C−C−C bond angles along its polymer chain?

An alcohol has the molecular formula $C_5H_{12}O$. It has several isomers.
Which isomer forms a yellow precipitate with alkaline aqueous iodine?

When compound X is heated under reflux with aqueous sodium hydroxide solution two products are formed: sodium ethanoate and hexan-1-ol.
What is compound X?

What is the major product Z of the following reaction?

The structure of compound Q is shown.

How many chiral centres are present in a molecule of Q?

Compound X has the infra-red spectrum shown.
What could be the identity of compound X?

Which reaction produces an organic anion with a good yield?

The definitions of many chemical terms can be illustrated by chemical equations.
Which terms can be illustrated by an equation that includes the formation of a positive ion?
1. first ionisation energy
2. heterolytic fission of a covalent bond
3. enthalpy change of atomisation

Which molecules have no overall dipole moment?
1. boron trifluoride
2. methane
3. phosphorus pentafluoride

Carbon exists in several different forms. Two of these forms are buckminsterfullerene and graphene. Buckminsterfullerene is a fullerene allotrope of carbon.
Which statements about buckminsterfullerene and graphene are correct?
1. Both have delocalised electrons.
2. Buckminsterfullerene has a giant molecular structure.
3. The carbon atoms in graphene form a tetrahedral lattice.

Carbon monoxide burns readily in oxygen to form carbon dioxide. What does this information suggest?
1. The +4 oxidation state of carbon is more stable than the +2 state.
2. The standard enthalpy change of formation of carbon dioxide is more negative than the standard enthalpy change of formation of carbon monoxide.
3. The value of the equilibrium constant for the reaction, $2 ext{CO}(g) + ext{O}_2(g) ightleftharpoons 2 ext{CO}_2(g)$, is likely to be high.

The catalytic converters fitted to cars remove pollutants from the exhaust gases. Some of the reactions that occur involve oxygen, which comes from the air. Which pollutants in the exhaust gases will react with oxygen on the surface of the catalytic converter?

Chlorine reacts with sodium hydroxide in two different ways depending upon the temperature.

reaction 1 \[Cl_2 + 2OH^- \rightarrow Cl^- + ClO^- + H_2O\]

reaction 2 \[3Cl_2 + 6OH^- \rightarrow 5Cl^- + ClO_3^- + 3H_2O\]

Which statements about these reactions are correct?

1 Reaction 2 requires a higher temperature than reaction 1.
2 The products of reaction 1 show chlorine in two different oxidation states.
3 The products of reaction 2 show oxygen in two different oxidation states.

In which of the reactions is the organic compound oxidised by the given reagent?

When the apparatus is set up as shown, an orange precipitate forms in test-tube Z.
What could compound Q be?

Chlorofluoroalkanes that diffuse into the stratosphere are broken down by ultraviolet radiation.
Radicals are generated that cause depletion of ozone.
What are these radicals?

The responses A to D should be selected on the basis of [Table_1].
A mixture of the three isomers of $C_2H_2Cl_2$ is polymerised. Which sequences will be seen within the polymer chains?